In this drama, based on a novel by Mary O'Hara, the relationship between humans and animals is paralleled as they struggle to live and find love on a wild ranch in Wyoming. The human story centers around a rancher's niece who falls in love with a neighboring rancher's son. The equine story follows the romantic exploits of a wild-eyed black mare and a wild white stallion, Thunderhead. One night, the sly stud sneaks upon the other's land and steals the mare. The rancher's boy brings them back. The rival ranchers get involved in a horse race and the niece's uncle wins over the other's pregnant mare. The two youngsters find love and as Thunderhead's baby is foaled, happiness ensues.